/**
 * Copyright (C) 2005-2009 Alfresco Software Limited.
 *
 * This file is part of the Spring Surf Extension project.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.extensions.surf.util;

import java.io.IOException;
import java.io.Writer;

/**
 * This is a direct copy of the JDK java.io.StringWriter class but modified to write
 * to a StringBuilder rather than the older, slower StringBuffer class. Obviously this
 * class is therefore not thread safe and synchronization should be provided at the
 * application level if required.
 * <p>
 * Original source comments:<i>
 * <p>
 * A character stream that collects its output in a string builder, which can then be
 * used to construct a string.
 * <p>
 * Closing a <tt>StringWriter</tt> has no effect. The methods in this class can be
 * called after the stream has been closed without generating an <tt>IOException</tt>.
 * </i>
 * 
 * @version 1.24, 04/07/16
 * @author Mark Reinhold
 */
public class StringBuilderWriter extends Writer
{
    private StringBuilder buf;

    /**
     * Create a new string writer, using the default initial string-builder size.
     */
    public StringBuilderWriter()
    {
        buf = new StringBuilder();
        lock = buf;
    }

    /**
     * Create a new string writer, using the specified initial string-builder size.
     * 
     * @param initialSize
     *            an int specifying the initial size of the builder.
     */
    public StringBuilderWriter(int initialSize)
    {
        if (initialSize < 0)
        {
            throw new IllegalArgumentException("Negative buffer size");
        }
        buf = new StringBuilder(initialSize);
        lock = buf;
    }

    /**
     * Write a single character.
     */
    public void write(int c)
    {
        buf.append((char) c);
    }

    /**
     * Write a portion of an array of characters.
     * 
     * @param cbuf
     *            Array of characters
     * @param off
     *            Offset from which to start writing characters
     * @param len
     *            Number of characters to write
     */
    public void write(char cbuf[], int off, int len)
    {
        if ((off < 0) || (off > cbuf.length) || (len < 0) || ((off + len) > cbuf.length) || ((off + len) < 0))
        {
            throw new IndexOutOfBoundsException();
        }
        else if (len == 0)
        {
            return;
        }
        buf.append(cbuf, off, len);
    }

    /**
     * Write a string.
     */
    public void write(String str)
    {
        buf.append(str);
    }

    /**
     * Write a portion of a string.
     * 
     * @param str
     *            String to be written
     * @param off
     *            Offset from which to start writing characters
     * @param len
     *            Number of characters to write
     */
    public void write(String str, int off, int len)
    {
        buf.append(str.substring(off, off + len));
    }

    /**
     * Appends the specified character sequence to this writer.
     * 
     * <p>
     * An invocation of this method of the form <tt>out.append(csq)</tt> behaves in exactly the same way as the
     * invocation
     * 
     * <pre>
     * out.write(csq.toString())
     * </pre>
     * 
     * <p>
     * Depending on the specification of <tt>toString</tt> for the character sequence <tt>csq</tt>, the entire
     * sequence may not be appended. For instance, invoking the <tt>toString</tt> method of a character buffer will
     * return a subsequence whose content depends upon the buffer's position and limit.
     * 
     * @param csq
     *            The character sequence to append. If <tt>csq</tt> is <tt>null</tt>, then the four characters
     *            <tt>"null"</tt> are appended to this writer.
     * 
     * @return This writer
     * 
     * @since 1.5
     */
    public StringBuilderWriter append(CharSequence csq)
    {
        if (csq == null) write("null");
        else write(csq.toString());
        return this;
    }

    /**
     * Appends a subsequence of the specified character sequence to this writer.
     * 
     * <p>
     * An invocation of this method of the form <tt>out.append(csq, start,
     * end)</tt> when <tt>csq</tt> is not
     * <tt>null</tt>, behaves in exactly the same way as the invocation
     * 
     * <pre>
     * out.write(csq.subSequence(start, end).toString())
     * </pre>
     * 
     * @param csq
     *            The character sequence from which a subsequence will be appended. If <tt>csq</tt> is <tt>null</tt>,
     *            then characters will be appended as if <tt>csq</tt> contained the four characters <tt>"null"</tt>.
     * 
     * @param start
     *            The index of the first character in the subsequence
     * 
     * @param end
     *            The index of the character following the last character in the subsequence
     * 
     * @return This writer
     * 
     * @throws IndexOutOfBoundsException
     *             If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt> is greater than <tt>end</tt>,
     *             or <tt>end</tt> is greater than <tt>csq.length()</tt>
     * 
     * @since 1.5
     */
    public StringBuilderWriter append(CharSequence csq, int start, int end)
    {
        CharSequence cs = (csq == null ? "null" : csq);
        write(cs.subSequence(start, end).toString());
        return this;
    }

    /**
     * Appends the specified character to this writer.
     * 
     * <p>
     * An invocation of this method of the form <tt>out.append(c)</tt> behaves in exactly the same way as the
     * invocation
     * 
     * <pre>
     * out.write(c)
     * </pre>
     * 
     * @param c
     *            The 16-bit character to append
     * 
     * @return This writer
     * 
     * @since 1.5
     */
    public StringBuilderWriter append(char c)
    {
        write(c);
        return this;
    }

    /**
     * Return the buffer's current value as a string.
     */
    public String toString()
    {
        return buf.toString();
    }

    /**
     * Return the string builder itself.
     * 
     * @return StringBuilder holding the current buffer value.
     */
    public StringBuilder getBuffer()
    {
        return buf;
    }

    /**
     * Flush the stream.
     */
    public void flush()
    {
    }

    /**
     * Closing a <tt>StringWriter</tt> has no effect. The methods in this class can be called after the stream has
     * been closed without generating an <tt>IOException</tt>.
     */
    public void close() throws IOException
    {
    }
}
